1. Field of the Invention
The present invention relates to an elastic wave device.
2. Description of the Related Art
Elastic wave devices have been widely used in, for example, filters of cellular phones. Japanese Unexamined Patent Application Publication No. 2002-100952 discloses one example of an elastic wave device including IDT (interdigital transducer) electrodes. Each of busbars of the IDT electrodes includes a lower layer wiring and an upper layer wiring laminated on the lower layer wiring.
Recently, in order to satisfy a demand for further size reduction of the elastic wave device, the distance between adjacent busbars of the IDT electrodes has gradually decreased due to design of arranging elastic wave resonators closer to each other in a direction perpendicular to an elastic-wave propagating direction. On the other hand, in a ladder filter, for example, a size of the IDT electrode of the elastic wave resonator taken along the elastic-wave propagating direction has increased to improve filter characteristics, and hence a length of the busbar has also increased. Accordingly, when the elastic wave resonators including the IDT electrodes, which have the busbars of two-layer structure and which are horizontally elongated as in Japanese Unexamined Patent Application Publication No. 2002-100952, are arranged close to each other, a formation failure or defect in the busbars is likely to occur, thus resulting in a possibility that short-circuiting may occur between the adjacent busbars. For that reason, it has been difficult to arrange the IDT electrodes in a sufficiently close relation, and to provide satisfactory size reduction of the elastic wave device.